This invention relates generally to transducer positioning apparatus and, more particularly, to improvements in apparatus for positioning a transducer head in relation to tracks on a recording medium such as magnetic tape.
An example of transducer positioning apparatus of this general type is disclosed in a copending application for U.S. patent, Ser. No. 853,397, filed in the name of D. L. Burdorf et al and entitled "Transducer Positioning Device", now U.S. Pat. No. 4,144,549. As described in that application, such apparatus includes a frame having a guide to direct the tape past the transducer head, and a cam mounted for rotation on the frame and having a series of graduated planar steps formed in its upper surface. The transducer head is carried by a platform assembly having a bearing post which is maintained in continuous contact with the steps of the cam, whereby controlled rotation of the cam causes the head to move upwardly or downwardly to predetermined positions corresponding to the positions of recording tracks on the magnetic tape.
The aforedescribed prior art device suffers from the drawback that the precision with which the transducer head can be positioned relative to the tracks on the tape cannot exceed the precision with which the steps of the cam are formed. To be operable in a system having a relatively high track density, such as, for example, one in which the spacing between adjacent tracks is 0.006 inches or less, the cam must be formed with extreme accuracy and precision. Consequently, the manufacturing costs associated with such apparatus are relatively high.
Another drawback to the aforedescribed prior art device arises because of the inclusion of a complex and relatively expensive mechanism for the manual adjustment of the vertical position of the transducer head with respect to the centers of the tracks on the tape. The adjustment mechanism includes means for lifting the entire cam relative to the frame, to effect a relative movement of the head. Although this adjustment mechanism has provided satisfactory performance in some situations, a simpler and less expensive alternative would be preferred, if it could provide equally satisfactory results.
It will be appreciated from the foregoing that there is still a need for apparatus which can accurately position a transducer head relative to tracks on a magnetic tape, without involving undue complexity or cost. The present invention fulfills this need.